Problem with mirroring and animation rigging
The main issue here is that you have several armatures, each with only 1 bone. But what you want is only 1 armature with several bones.
You can join the armatures with Ctrl+J. But you need to do some clean-up first. Most of your objects have a Mirror modifier. I would apply them and make a full rig with mirrored bones. If you want to keep the Mirror modifiers for some reason you need to move the Armature modifier below the Mirror modifier on the stack.
Clean-up

select all object and rotate them by -90° around the Z-axis (R, Z, -90). This places the dragon correctly. The front is in the front view and the side is the side view. This way you can mirror bones along the X-axis if you name them with &quot;.L&quot;, &quot;_L&quot;, &quot;.left&quot; or &quot;_left&quot;, and &quot;.R&quot;, etc, respectively.
select the head's aramature (szyja), go to Pose mode, select all bones(well, it's only 1) with (A), and clear all transformations (menu: Pose &gt; Clear Transformation &gt; All)

If you go to front view (Numpad 1 or menu: View &gt; Viewpoint &gt; Front) the dragon should now look at you

remove all Armature () modifiers from every object. Apply the mirror modifiers if you want, do it top-down from the stack.
join all Armature objects (grzywa...*, Oko, szczęka, dzialo szczekowe. kosci, szyja) with Ctrl+J. The last one you select will be the remaining main armature. If a mesh moves then check the modifiers for an Armature modifier and remove it.
apply Location, Scale, Rotation for the armature (Ctrl+A, All Transformations)
optional: this should be done for the mesh objects, too, but the Mirror modifier settings must be adjusted (mirror X-axis for the head, ...)
optional: if you have applied the mirrors, rename all the bones on the dragon's left side (=right side from your point of view) to Kosc- mocowanie mk1.L. Then use the menu: Armature &gt; Symmetrize in Edit mode to let create the bones on the right side.
select all the mesh objects and the armature, then parent them (Ctrl+P, With Empty Groups in Object mode). Empty Groups will use the still existing weights. Adjust the modifier stack if you have Mirror modifiers.
check the weight paint for the eyes and the jaw. There seem to be some &quot;rogue&quot; vertices that have a different weight.
for better control make a bone hierarchy. Parent the bones (with offset). Something like root -&gt; neck -&gt; head -&gt; mane, jaw, eyes, &quot;ears&quot;. This way everything will rotate with the head. This doesn't work with a flat hierarchy as shown in the screenshot.